The present invention relates to a bearing structure and a motor.
Japanese Laid-Open Patent Publication No. 11-164510 discloses a motor that includes a bearing structure including a rotation shaft, a bearing that rotationally supports the rotation shaft, and a housing including a bearing accommodation recess that accommodates and holds the bearing. In the motor of the publication, the bearing of the motor includes an arcuate outer circumferential surface that bulges, or projects, outward in the radial direction from the axial ends toward the axially middle portion of the bearing. Further, the bearing accommodation recess includes an inner circumferential surface having a circular cross-section in a direction orthogonal to the axis of the bearing. The arcuate surface of the bearing is located in a portion of the bearing that is close to a bottom end of the bearing accommodation recess. The bearing is held in the bearing accommodation recess so that the arcuate surface of the bearing abuts against the inner circumferential surface of the bearing accommodation recess over the entire circumference.
However, in the above bearing structure, when the inner circumferential surface of the bearing accommodation recess has a large roundness error, the inner circumferential surface of the bearing accommodation recess contacts the arcuate surface of the bearing at fewer points, and the inner circumferential surface of the bearing accommodation recess may contact the arcuate surface of the bearing at three points. In addition, the inner circumferential surface of the bearing accommodation recess does not contact the arcuate surface of the bearing at the fixed locations. In such a case, the position of the bearing relative to the bearing accommodation recess varies between motors. This displaces the rotation shaft, which is supported by the bearing. Thus, the rotation axis of the rotation shaft may be located at different positions in different motors.